Radio-frequency (RF) technology is a transmission technology having been used for a long time. It is applied to various radio broadcasting and wireless network applications. Radio broadcasting is a widely known application technology. In early days, radio broadcasting includes frequency-modulation (FM) and amplitude-modulation (AM) broadcasting stations. Nowadays, radio broadcasting further includes digital broadcasting, such as digital video broadcasting (DVB) and digital audio broadcasting (DAB). Wireless networks provide users with the ability of wirelessly connecting to the networks with electronic apparatuses supporting the network transmission interface, thereby increasing mobility and convenience for users using the electronic apparatuses. However, no matter radio broadcasting or wireless networks, the problem of band jamming is inevitable. Accordingly, quality of data transmission in radio broadcasting or wireless networks will be affected by jamming sources. Besides, unmanned vehicle systems using radio interfaces for data transmission or control signals will be thereby affected by jamming sources as well.
Unmanned aerial vehicle systems include at least an aerial vehicle, at least a remote guidance and control apparatus, at least a data link, and a payload. Normally, the data link of a relatively complete unmanned aerial vehicle system possesses communication channels in a plurality of frequency bands for ensuring signals transmitted between the remote guidance and control apparatus and the unmanned aerial vehicle will not lock out. The application technologies of modern remote guidance and control apparatus and the data link have developed to the extent that a guidance and control station can operate a plurality of unmanned aerial vehicles of different models synchronously, or a guidance and control station can remotely guide and control a plurality of unmanned aerial vehicles of the same model synchronously. When a plurality of unmanned aerial vehicles operates synchronously and is remotely guided and controlled by a single remote guidance and control apparatus, operators of the remote guidance and control apparatus can not judge immediately communication quality according to the communication conditions between the unmanned vehicles and the remote guidance and control apparatus for executing corresponding correcting processes. In particular, when the communication signals between the unmanned vehicles and the remote guidance and control apparatus is jammed by unidentified strong signal waves, it is even necessary to perform corrections for improving communication quality.
Although in general, unmanned vehicles possesses the ability of autonomic lockout motion, when the communication signals between the remote guidance and control apparatus and the unmanned vehicles are lost, the remote guidance and control apparatus will not be able to acquire the locations of the unmanned vehicles. In particular, under the situation of a plurality of unmanned aerial vehicles operating synchronously, the communication conditions between the remote guidance and control apparatus and the plurality of unmanned aerial vehicles are more complex. If the communication signals between the remote guidance and control apparatus and one of the unmanned vehicles are lost, the unmanned aerial vehicle with signals lost will impact with other unmanned aerial vehicles, or the unmanned aerial vehicle with signals lost will impact with manned aerial vehicles, and thereby irretrievable disasters will result. Accordingly, when a single remote guidance and control apparatus remotely guides and controls multiple unmanned vehicles that are operating under complicated environment with a plurality of data links, jamming on the data link between each of the unmanned vehicles and the remote guidance and control apparatus by other data links is inevitable. Consequently, unexpected out-of-control situations on the unmanned vehicles will result.
FIG. 1A shows a schematic diagram of uplink jamming on an unmanned vehicle system according to the prior art, and FIG. 1B shows a schematic diagram of downlink jamming on an unmanned vehicle system according to the prior art. The difference between FIG. 1A and FIG. 1B is that the jamming source 10 in FIG. 1A drives directly the unmanned vehicle 20 unable to receive the control signals of the remote guidance and control apparatus 30 smoothly, and consequently causes the remote guidance and control apparatus. 30 unable to control the unmanned vehicle 20 smoothly. The jamming source 10 in FIG. 1B jams the remote guidance and control apparatus 30 from transmitting control signals to the unmanned vehicle 20, and thereby causes the remote guidance and control apparatus 30 unable to detect the status of the unmanned vehicle 20 smoothly. Besides, in addition to unmanned aerial vehicles, there exists a plurality of manned aerial vehicles in the air. There also exists at least one frequency band of communication channels between each of the manned aerial vehicles and the corresponding ground control station. Thereby, the frequency bands used by the plurality of manned aerial vehicles are a plurality of jamming sources for the communication channels between the unmanned aerial vehicles and the remote guidance and control apparatus. Therefore, it is necessary that the unmanned aerial vehicles or the remote guidance and control apparatus 30 are capable of judging unjammed frequency bands, and of switching the communication channels therebetween to the unjammed frequency bands, so that the remote guidance and control apparatus can continuously control the unmanned aerial vehicles.
According to the problems described above, a novel method of jamming prevention capable of overcoming the traditional drawback of signal loss between the remote guidance and control apparatus and the unmanned vehicles, and of preventing near real-timely jamming sources affecting communications therebetween is highly desired. The method of near real-time band jamming prevention for remote guidance and control apparatuses with multiple frequency bands according to the present invention can solve the problem describe above.